The overall aim of this study is to provide a comprehensive picture of the course and outcome of four specific personality disorders (PDs): schizotypal (STPD), borderline (BPD), avoidant (AVPD), and obsessive- compulsive (OCPD). Using a prospective longitudinal, repeated measures design we will develop the same basic knowledge about course and outcome for the PDs that has previously resulted from similar investigations of affective and anxiety disorders. The absence of comparable data for individuals diagnosed with PDs represents an important gap in knowledge. To accomplish our overall aim we propose three approaches: I. descriptive, II. predictive, and III. validating. The descriptive approach will provide the basic data on stability of psychopathology and social impairment that allows comparison between the PDs and to similar data from Axis I disorders. The predictive approach will yield basic clinical insights into the determinants of prognosis within and across PDs. The validating approach will examine the homogeneity of descriptive and longitudinal features for the PDs as defined by the DSM system and how this compares with alternative schemes. To accomplish these aims, this proposal requests funds to recruit, rigorously assess, and follow a total sample of 750 subjects, aged 18 to 45, i.e., 150 of each of the four PDs and 150 controls with major depressive disorder (MDD). The sample will be large enough and sufficiently diverse ethnically to attain results generalizable to most clinical settings and to examine the application of several dimensional approaches.